Polyalkylene glycol alkyl or haloalkyl polyphosphonates used as flame retardants in polyurethane foam

ABSTRACT

Polyalkylene glycol alkyl or haloalkyl polyphosphonates having the idealized formula: ##EQU1## WHEREIN R is a polyalkylene glycol residue, R&#39; is alkyl or haloalkyl and n is 1-100, are prepared by transesterifying a tertiary phosphite with a polyalkylene glycol and rearranging the resultant polyalkylene glycol alkyl or haloalkyl polyphosphite to a polyalkylene glycol alkyl or haloalkyl phosphonate by the action of heat and an Arbuzov rearrangement catalyst.

This is a division, of application Ser. No. 282,642 filed Aug. 21, 1972,now U.S. Pat. No. 3,855,360.

BACKGROUND OF THE INVENTION

In the polyurethane field, increased interest is being shown incompounds which can be added to the polyurethane polymers to act asflame retardant agents. Particular interest is being shown in compoundswhich have functional groups reactive with the polyol or polyisocyanateused in preparing the polyurethane so that the flame retardant agent canbe copolymerized into the polymer chain. One such group of reactiveflame retardants are the polyalkylene glycol phosphites such as thosedescribed in U.S. Pat. No. 3,009,939. However, these materials, due totheir high OH number and crosslinking tendency, are unsuitable for usein flexible urethane foams. In U.S. Pat. Nos. 3,081,331 and 3,142,651,there is disclosed a method of forming polyalkylene glycolpolyphosphites having up to 10 phosphite groups in the polymer chain byreacting a trialkyl phosphite with a polypropylene glycol in a molarratio of 2.1 to 2.5 moles of glycol per mole of phosphite. Thesematerials are also unsuitable for use in flexible urethane foams as aresult of their high OH numbers and their tendency to crosslink.

Another attempt at employing reactive flame retardants, described inU.S. Pat. Nos. 3,142,651 and 3,092,651, involves the use ofpolypropylene glycol poly-hydrogenphosphonates produced by a thermalpolymerization. Likewise, polyalkylene glycol hydrogen polyphosphonateshave also been produced by transesterifying a secondary hydrogenphosphonate with a polyalkylene glycol according to the procedureoutlined in British Pat. Nos. 796,446 and 1,011,118. However, many ofthese materials have relatively high acidity, causing them to react withand thereby deactivate the catalyst systems generally used in theformation of polyurethane polymers such as, for example, tertiary aminecompounds. The former method has the additional drawback ofcontamination of the product by the alkylene glycol by-product, whichcontaminant is not easily removed.

In order to increase the flame retardancy of some of the above describedphosphorus compounds, which have low phosphorus content, the prior arthas attempted to incorporate various halogen containing substituentsinto the above described molecules. Thus, U.S. Pat. Nos. 3,159,605 and3,167,575, describe the reaction of halogenated methanes with thesecompounds. Likewise, U.S. Pat. Nos. 3,131,206 and 3,328,493, describethe reaction of chloral with them. However, these materials, like theirprecursors, have many drawbacks. In particular, these products have highOH numbers and low phosphorus content thereby rendering them lesssuitable as flame retardants in flexible urethane foams.

In addition to these above-mentioned prior art references, Review InMarcomolecular Chemistry, Vol. II, N.Y.C. 1967, discloses thatpolyalkylene glycol alkyl phosphonates have been prepared by reacting analkyl phosphonic acid dichloride with a polyalkylene glycol. Thisprocedure was originally reported by Korshak et al, inVzsokomolekuylarnye Soedineniya 2, 427-32 (1960). In a subsequentarticle by Tormosina et al, Khim. Khim. Tekhonol. 1968, 31-41, thepolyalkylene glycol alkyl phosphonates prepared by this route aredisclosed as containing unhydrolyzed chlorine and being too acidic foruse in polyurethane foam. Furthermore, Korshak et al, Izv. Akad. Nauk.SSSR, Otd. Khim. Nauk. 1963(6), 1095-1100, disclose the preparation ofpolyalkylene glycol alkyl phosphonates by transesterifyingdimethylmethylphosphonate with diethylene glycol. The product, however,is disclosed as being characterized with an acid number of from 240 to400 mg. of KOH/gm. of sample and accordingly is also unsuitable for usein polyurethane foam.

In U.S. Pat. Nos. 3,798,290, and 3,819,750, there are disclosed novelpolyalkylene glycol vinyl phosphates and novel mixed polyalkylene glycolvinyl phosphates and phosphites which are prepared by reacting ahalogenated carbonyl compound with a polyalkylene glycol alkylpolyphosphite. While these vinyl phosphonates yield polyurethane foamhaving excellent flame retardant and physical characteristics, they haverecently been found to impart a slight odor to the foam which may beconsidered objectionable.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide novelpolyalkylene glycol alkyl or haloalkyl polyphosphonates which aresuitable as flame-retardants.

Another object of this invention is to provide polyalkylene glycol alkylor haloalkyl polyphosphonates suitable as flame retardants for urethanefoams, and in particular flexible and rigid urethane foams.

A further object of the present invention is to provide polyalkyleneglycol alkyl or haloalkyl polyphosphonates which, while impartingexcellent flame-retardancy to urethane foam, are further characterizedby superior chemical and physical properties, such as, for example,stability and low acidity, so as to yield foams having good color, goodappearance, no odor and generally good physical properties.

A further object of this invention is to provide urethane foams havingincorporated therein these novel polyalkylene glycol alkyl or haloalkylpolyphosphonates.

A still further object of the present invention is to provide novelprocesses for the preparation of these polyalkylene glycol alkyl orhaloalkyl polyphosphonates.

Further advantages of the present invention will become obvious from areading of the disclosure which follows hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has now been discovered that by heating certain polyalkylene glycolalkyl polyphosphites in the presence of an alkyl halide, there isobtained polyalkylene glycol alkyl polyphosphonates which are polymersbeing particularly characterized by their excellent flame retardantproperties and low acidity. In addition, the present polyalkylene glycolalkyl polyphosphonates are characterized by low OH numbers, lack oftendency to gel initially or crosslink in the final foamed product, highstability during and subsequent to the foam forming process, and theoverall general ability to yield urethane foams which have superiorflame retardancy and excellent physical properties, such as thesubstantial lack of scorch, discoloration, odor and other undesirableproperties.

The polyalkylene glycol alkyl polyphosphonates of the present inventioncan be represented by an idealized formula as follows: ##EQU2## whereinR is a polyalkylene glycol residue; R' is alkyl or haloalkyl and n is anumber in the range of from about 1 to 100, and preferably from about 5to 20. Preferably, R' is C₁ -C₁₀ alkyl or C₁ -C₁₀ haloalkyl. Haloalkylis intended to include for example, chloromethyl, bromomethyl,chloroethyl, bromoethyl, dichloropropyl, and the like. Most preferably,however, R' is methyl. The term polyalkylene glycol residue, designatedby R, is meant to define that portion remaining after two hydroxylgroups have been removed from a polyalkylene glycol having the formula:

    HO -- R"O ).sub.x H

wherein R" is an alkylene group of 2 to about 20 carbon atoms, which isstraight chained, branch chained, or a mixture thereof, with the provisothat at least two carbon atoms separate successive oxygen atoms, and xdesignates the number of repeating alkylene ether units and is normally2 to about 20. For the purposes of the present invention, R is Formula Iabove, is most preferably a diethylene glycol residue.

As indicated above, Formula I represents an idealized structure of thefinal products of the present invention. It is clear to one skilled inthe art that as a result of the polymeric nature of these polyalkyleneglycol alkyl polyphosphonates of the present invention and their methodof preparation, these products are complex mixtures. Thus, for example,these mixtures will include in addition to the hydroxy terminatedpolymers, as represented by the idealized structure of Formula I above,a statistical quantity of polymeric product wherein the terminal hydroxygroups are either partially or fully replaced by ##EQU3## groups whereinR' is as defined above. Furthermore, the polymer products of the presentinvention will also include a statistical quantity of polymeric productwherein R' of Formula I above, is replaced by an R group, also asdefined above, and in turn the alkyl or haloalkyl phosphonatecondensates thereof. Therefore, it is to be understood that the presentinvention as particularly encompassed by the structure of Formula Iabove, is obviously intended to include these polymeric materialsindividually as well as in combination.

The compounds of the present invention are prepared by heating apolyalkylene glycol alkyl or haloalkyl polyphosphite which has anidealized formula as follows: ##EQU4## wherein R, R' and n are asdescribed above, in the presence of an alkyl or aralkyl halide. Thispolyphosphite of Formula II above, is formed by transesterifying atertiary phosphite with a polyalkylene glycol in a molar ratio of fromabout 0.8 to about 1.5 and preferably from about 0.8 to about 1.2 molesof phosphite per mole of glycol.

The preparation of these polyalkylene glycol polyphosphites of FormulaII is disclosed in the above-noted copending applications and inaddition are disclosed and claimed in co-pending U.S. application SerialNo. 483,606, filed on June 27, 1974, said application being acontinuation of U.S. application Ser. No. 166,295 filed on July 26,1971, by Silvio L. Giolito and now abandoned.

The tertiary phosphite used to prepare these polyalkylene glycol alkylor haloalkyl polyphosphite starting materials of Formula II has thegeneral formula: ##EQU5## wherein each R' is as defined above. Thus,illustrative of the tertiary phosphites which can be employed are thefollowing: trimethyl phosphite, triethyl phosphite, tripropyl phosphite,tributyl phosphite, trioctyl phosphite, dimethyl ethyl phosphite,diethyl methyl phosphite, tris(chloroethyl) phosphite,tris(2-chloropropyl) phosphite, tris(dichloropropyl) phosphite, and thelike. Trimethyl and triethyl phosphite are particularly preferred, withtrimethyl phosphite being most preferred.

The above described tertiary phosphite is transesterified with apolyalkylene glycol having the formula:

    HO -- R"O ).sub.x H

wherein R" and x are as described above. Illustrative of thepolyalkylene glycols which can be employed in the present invention arethe following: diethylene glycol, triethylene glycol, dipropyleneglycol, tripropylene glycol, tributylene glycol, polyethylene glycols,polypropylene glycols wherein the average number of ether units is 14,trihexylene glycol and the like. Particularly preferred glycols arediethylene glycol, dipropylene glycol and tripropylene glycol, withdiethylene glycol being most preferred. It is understood that thepropylene glycols can be primary, secondary, or mixtures thereof.

In order to form the polyphosphite starting material of Formula IIabove, the tertiary phosphite and the polyalkylene glycol must bereacted in critical proportions. Thus, the tertiary phosphite should bepresent in an amount from about 0.8 to about 1.5 moles per mole of theglycol. The preferred range for this preparation is from about 1 toabout 1.2 moles of phosphite per mole of glycol. If the glycol isreacted in quantities substantially greater than about 1 to 1 with thephosphite, the product will contain primarily the undesirable mono, di,tri and tetraphosphites and, more importantly, will have a substantialamount of free hydroxyalkyleneoxyalkylene groups attached to thephosphite group.

Where trimethyl phosphite and diethylene glycol are utilized to preparethe polyphosphite of Formula II, it now has been found for the purposesof this invention, that it is most preferred to employ 1.1 moles ofphosphite to 1 mole of glycol.

The above disclosed transesterification reaction is normally conductedby mixing the phosphite and glycol in the presence of any of the wellknown transesterification catalysts. Particularly useful catalysts arethe alkali metal alcoholates and phenolates such as sodium methylate,sodium decylate, sodium phenolate, and the like. These catalysts arenormally employed in an amount from about 0.1 to about 10 percent, byweight, of the entire reaction mixture. Again, with particular regard tothe transesterification reaction between trimethyl phosphite anddiethylene glycol it now has been found that no catalyst is necessary,although, obviously if desired, one may be employed. The reactiontemperature should initially be kept below the boiling point of thelowest boiling reactant in order to avoid the loss of that reactant.Although the reaction can be conducted at room temperature, i.e., 20°C., it is preferred to conduct it as close to the upper limit aspossible in order to increase the rate of reaction. Thus, in the casewhere trimethyl phosphite is employed as the tertiary phosphite, thereaction temperature is preferably within the range of 60° C. to 110° C.and should not be allowed to rise above 110° C. until at least one R'group on each of the phosphite molecules has been replaced with apolyalkylene glycol. This can normally be determined by monitoring theamount of methanol which has been evolved.

While the reaction can be run to completion at these temperature ranges,it has been found to be advantageous at times to raise the temperatureafter this initial replacement of one of the R' groups on the startingphosphite up to a limit of about 150° C. and most preferably up to about120° C. As stated above, the point at which the temperature should beraised can be determined by monitoring the amount of by-product alkanolproduced. Thus, when one mole of trimethyl phosphite is beingtransesterified, the reaction temperature can be raised after one moleof methanol has been evolved. The transesterification is completed whentwo moles of methanol have been evolved. The degree of polymerization ofthe polyphosphite can be controlled to an extent by varying the time ofthe reaction. Furthermore, the polymer length can be monitored bymeasuring the viscosity buildup during the reaction according to wellknown techniques.

The transesterification reaction can optionally be carried out in thepresence of an inert solvent, however, such solvent is not required forthe practice of the present invention. The term inert solvent is meantto designate any solvent which does not react with the startingmaterials or products of the present invention. Suitable solventsinclude the alkylated benzenes such as ethyl benzene, diethyl benzene,toluene, the xylenes, and substituted benzenes such aso-dichlorobenzene, chlorobenzene, anisole and the like.

The polyalkylene glycol alkyl or haloalkyl polyphosphite produced by theprocess described above and represented by Formula II, is then heated inthe presence of an Arbuzov rearrangement catalyst whereby arearrangement is effected and the polyalkylene glycol alkyl or haloalkylpolyphosphonate of Formula I above is formed. This rearrangementreaction may be carried out over a wide temperature range. Generally,temperatures from about 160° C. to about 230° C. are employed, with thepreferred range being from about 165° C. to about 200° C. Although, anyArbuzov rearrangement catalyst may be employed, the alkyl halides andaralkyl halides are preferred. Illustrative of these are, for example,methyl iodide, ethyl iodide, methyl bromide, methyl chloride, butyliodide, butyl chloride, aryl iodide, nonyl bromide, octyl iodide, benzylbromide, benzyl iodide, chloromethylnapthalene, triphenylbromomethane,and the like. Methyl iodide is most preferred. Among other Arbuzovrearrangement catalysts are included elemental iodide and alkali metalhalides, such as sodium iodide, potassium iodide, potassium fluoride,sodium bromide, lithium iodide, and the like. Any catalyticallyeffective amount of the catalyst may be employed and generally is in therange of from about 0.05 to about 5% by weight. Preferably from about0.1 to about 0.2% of catalyst is used.

Similar to the transesterification reaction described above, therearrangement of the polyalkylene glycol alkyl or haloalky polyphosphitecan optionally be carried out in the presence of an inert solvent,however, such solvent is not required for the practice of the presentinvention. Thus, the same solvent as employed during thetransesterification reaction or a different solvent may be used duringthe rearrangement reaction. Suitable solvent include the alkylatedbenzenes such as ethyl benzene, diethyl benzene, toluene, the xylenesand substituted benzenes such as o-dichlorobenzene, chlorobenzene,anisole and the like. Furthermore, in performing the rearrangementreaction, the catalyst may be added all at once or in increments to thepolyalkylene glycol alkyl or haloalkyl polyphosphite intermediate.Moreover, if a solvent is being employed a mixture of said solvent andcatalyst may be added in increments. When a solvent is being employed,the rearrangement is generally completed in from about 2 to about 20hours, whereas the reaction is completed in from about 5 minutes toabout one hour in the absence of a solvent, depending upon thetemperature being employed. The final product, i.e. the polyalkyleneglycol alkyl polyphosphonate is essentially neutral and generally doesnot have an acid number in water in excess of 15 miligrams of KOH pergram of sample (in water). Accordingly, there is no need to neutralizethe polyalkylene glycol alkyl or haloalkyl polyphosphonates preparedaccording to the present invention. However, if desirable, thepolyalkylene glycol alkyl or haloalkyl polyphosphonate may be furtherneutralized by employing any of the conventional means to do so, such astreatment with ethylene oxide, propylene oxide, epichlorohydrin and thelike.

The novel polyalkylene glycol alkyl or haloalkyl polyphosphonates of thepresent invention are particularly characterized by their ability tocopolymerize with polyisocyanates employed in forming polyurethanes, bytheir relatively low OH numbers and low acidity, by their highphosphorus content, and by their high flame retardant and stabilizedcharacteristics especially in the final foams. These compounds cancompletely replace the polyols normally employed in forming the urethanefoams or they can be used in combination with the polyols, therebyyielding foams with greatly improved flame resistance. Since they reactin the foam forming process, their residues are chemically bonded intothe foam, thereby giving them high performance such as durability, evenupon high temperature aging or after water or solvent extraction. Asstated above, the acid numbers in water of the polyalkylene glycol alkylor haloalkyl polyphosphonates of the present invention are generally inthe range of from essentially neutral to about 15 milligrams of KOH pergram of sample, and most usually from essentially neutral to about 2milligram of KOH per gram of sample. This lack of or low acidity, incontrast to the higer acidity of prior art compounds, makes thecompounds of the present invention essentially unreactive toward thepolymerization catalysts employed in producing the polyurethane foams.As mentioned above, the present compounds also have relatively lower OHnumbers as compared to the prior art flame retardants and, therefore,can be used in flexible urethane foams without materially affecting thephysical properties of such foams. By the term relatively low OHnumbers, it is meant to designate OH numbers below about 150 andpreferably below 100. The compounds of the present invention are furthercharacterized by the fact that they are substantially linear polymerswhen compared to those disclosed in the prior art.

The polyalkylene glycol alkyl or haloalkyl polyphosphonates of thepresent invention, when employed in sufficient quantity, will yield aself-extinguishing polyurethane foam. This characteristic isparticularly important in the area of flexible foams due to the wide useof such foams in hospitals, homes and automobiles. Normally, thecompounds of the present invention can be employed in amounts of fromabout 3 to about 30 percent, by weight, of the entire foam formingmixture to yield self-extinguishing foams. Preferably, they are employedin amounts from 3 to 10 percent, by weight, of the entire mixture. It isunderstood, however, that this amount will vary depending upon theparticular foam being used, and that the required proportions can easilybe determined with a minimum amount of blending work.

While the compounds of the present invention are primarily intended foruse in urethane foams, it is contemplated that they can also be used ina wide variety of polymeric systems. Illustrative of these systems are:polyester, polyolefins, cellulose ethers and esters, urethane coatingsand elastomers, polymethyl methacrylates, polyvinyl chlorides, and manyothers. Furthermore, the compounds of the present invention can also beemployed in combination with any of the known flame retardants for foamsor polymeric systems such as, for example, tris(dichloropropyl)phosphite, tris(chloroethyl) phosphite, tris(dibromopropyl) phosphite,and the like.

The polyurethane foams within which the flame retardants described aboveare incorporated are well known in the art. They are produced by thereaction of a di- or polyisocyanate and a di- or polyhydroxy (polyol)compound in the presence of a blowing agent and a catalyst. The foamscan be made by any of the basic techniques used in foam formation; i.e.the prepolymer technique, the semi-prepolymer technique or the one-shotprocess. These techniques are well known and described in thepolyurethane art.

As examples of organic di- and polyisocyanates which can be employed tomake the polyurethane foams there can be employedtoluene-2,4-diisocyanate; toluene-2,6-diisocyanate;4-methoxy-1,3-phenylene diisocyanate; diphenylmethane-4,4'-diisocyanate; 4-chloro-1,3-phenylene-diisocyanate;4-isopropyl-1,3-phenylene-diisocyanate;4-ethoxy-1,3-phenylene-diisocyanate; 2,4-diisocyanate-diphenylether;3,3'-dimethyl-4,4'-diisocyanato-diphenyl methane; mesitylenediisocyanate; durylene diisocyanate; 4,4'-methylene-bis(phenylisocyanate); benzidine diisocyanate; o-nitrobenzidinediisocyanate; 4,4'-diisocyanatedibenzyl;3,3'-bitolylene-4,4'-diisocyanate; 1,5-naphthalene diisocyanate;tetramethylene diisocyanate; hexamethylene diisocyanate; decamethylenediisocyanate; toluene-2,4,6-triisocyanate; tritolylmethanetriisocyanate; 2,4,4'-triisocyanatodiphenyl ether; the reaction productof toluene diisocyanate with trimethylolpropane; and the reactionproduct of toluene diisocyanate with 1,2,6-hexanetriol.

Alternatively, as the polyisocyanate there can be used prepolymers madeby reacting one or more of the above polyisocyanates with a di- orpolyhydroxy compound such as a polyester having terminal hydroxylgroups, a polyhydric alcohol, glycerides or hydroxy containingglycerides, etc. These prepolymers should have terminal isocyanategroups and, to insure their presence, it is frequently desirable toemploy an excess of 5% or more of the polyisocyanate in forming theprepolymer. Typical examples of such prepolymers having isocyanate andgroups are those formed from toluene diisocyanate and polyhydroxycompounds. In most cases, a mixture of 80% of the 2,4-isomer and 20% ofthe 2,6-isomer of toluene diisocyanate is employed in making theseprepolymers. Thus, there can be used the prepolymers resulting from thereaction between toluene diisocyanate and caster oil, blown tung oil,blown linseed or blown soya oil, and of toluene diisocyanate and thepolyester of ethylene glycol, propylene glycol and adipic acid.

Examples of suitable polyols are polyethylene glycol, polypropyleneglycols, ethylene glycol, diethylene glycol, triethylene glycol,propylene glycol, dipropylene glycol, tripropylene glycol,1,4-butanediol, thiodiglycol, glycerol, trimethylolethane,trimethylolpropane, ether triols from glycerine and propylene oxide,other containing triols from 1,2,6-hexanetriol and propylene oxide,sorbitol-propylene oxide adducts, pentaerythritol-propylene oxideadducts, trimethylol phenol, oxypropylated sucrose, triethanolamine,pentaerythritol, diethanolamine, caster oil, blown linseed oil, blownsoya oil, N,N,N',N'-tetrakis(2-hydroxyethyl) ethylenediamine,N,N,N',N'-tetrakis(2-hydroxypropyl) ethylenediamine,N,N,N',N",N"-pentakis (2-hydroxypropyl) diethyl triamine,N,N,N',N",N"-pentakis(2-hydroxyethyl) diethylene triamine, mixedethylene glycolpropylene glycol adipate resin, polyethylene adipatephthalate and polyneopentylene sebacate.

In preparing the foamed polyurethanes there can be used any of theconventional basic catalysts such, for example, as N-methyl morpholine,N-ethyl morpholine, 1,2,4-trimethylpiperazine, trimethyl amine, triethylamine, tributyl amine and other trialkyl amines, the esterificationproduct of adipic acid and diethylethanolamine, triethyl amine citrate,3-morpholinopropionamide, 1,4-bis(2-hydroxypropyl)-2-methylpiperzine,2-diethylaminoacetamide, 3-diethylaminopropionamide,diethylethanolamine, triethylenediamine, N,N,N',N'-tetrakis(2-hydroxypropyl) ethylenediamine, N,N'-dimethylpiperazine,N,N-dimethylhexahydroaniline, tribenzylamine and sodium phenolate. Alsoapplicable are tin compounds, e.g. hydrocarbon tin alkyl carboxylatessuch as dibutyltin dilaurate, dibutyltin diacetate, dibutyltindioctoate, tributyltin monolaurate, dimethyltin diacetate, dioctyltindiacetate, dilauryltin diacetate, dibutyltin maleate, hydrocarbon tinalkoxides, e.g. dibutyltin diethoxide, dibutyltin dimethoxide,diethyltin dibutoxide as well as other tin compounds, e.g. octylstannoicacid, trimethyltin hydroxide, trimethyltin chloride, triphenyltinhydroxide, trimethyltin chloride, triphenyltin hydride, triallyltinchloride, trioctyltin fluoride, dibutyltin dibromide,bis-(carboethoxymethyl) tin diiodide, tributyltin chloride, trioctyltinacetate, butyltin trichloride, octyltin tris(thiobutoxide), dimethyltinoxide, dibutyl tin oxide, dioctyltin oxide, diphenyltin oxide, stannousoctanoate, and stannous oleate.

Any of the conventional surfactants can be used in amounts of 1% orless, e.g. 0.2% by weight of the composition. The preferred sufactantsare silicones, e.g. polydimethyl siloxane having a viscosity of 3 to 100centistokes, triethoxydimethyl polysiloxane, molecular weight 850copolymerized with a dimethoxypolyethylene glycol having a molecularweight of 750.

The foaming reaction can be carried out by adding water to the polyolprior to or simultaneously with the addition of the polyisocyanate.Alternatively, foams can be prepared by the use of a foaming or blowingagent. These are usually a liquefied, halogen substituted alkane such,for example, as methylene chloride. Especially preferred are thosehalogen substituted alkanes having at least one fluorine atom in theirmolecules such as trichlorofluoromethane, dichlorodifluoromethane,dichloromonofluoromethane, chlorodifluoromethane,dichlorotetrafluoroethane. In using these blowing agents, they areuniformly distributed in either the polyol reactant or thepolyisocyanate reactant whereupon the reactants are mixed permitting thetemperature of the mixture to rise during the ensuing reaction above theboiling point of the liquefied gas so as to produce a porouspolyurethane. It should be noted that foaming may also be affected bycombining the use of a blowing agent with the addition of water to thepolyol.

Having generally described the invention, the following examples aregiven for purposes of illustration. It will be understood that theinvention is not limited to these examples but is susceptible todifferent modifications that will be recognized by one of ordinary skillin the art.

EXAMPLE 1

To a 30 gallon reactor is charged 50.6 pounds of diethylene glycol, 65.6pounds of trimethylphosphite, 123 pounds of O-dichlorobenzene and 48grams of sodium methoxide (25% solution in methanol). The reactionmixture is heated (in a nitrogen atmosphere) to about 100° C. andmaintained at their temperature for about 21/4 hours with removal ofvolatiles. A vacuum is slowly applied to the reactor (to 54 mm Hg) withthe temperature cooling to 180° F., the volatiles are further strippedin this manner for 45 minutes.

To the resultant product is added 120 grams of methyl iodide and 14pounds of O-dichlorobenzene. The resultant mixture is heated (in anitrogen atmosphere) to reflux and held at about 165° C. for 1/2 hour.The reaction temperature is increased to about 180° C. and maintainedthere for an additional 7-1/2 hours with removal of volatiles. Theproduct obtained is a viscous clear colorless liquid with an acid numberof 0.54 milligrams of KOH per gram of sample in water and neutral in CH₃OH. Analysis of the product confirmed the structure to bepoly(diethylene glycol methylphosphonate), having an average n value of6.5.

Analysis: % P = 17.9. OH Number = 62.

EXAMPLE 2

To a 0.5 liter 3-necked round bottom flask equipped with a mechanicalstirrer, thermometer and distillation head is charged 106 grams (1 mole)of diethylene glycol, 136.4 grams (1.1 moles) of trimethylphosphite and0.25 grams of sodium methoxide (25% in methanol). The reaction mixtureis vigorously agitated while it is heated to from about 100° C. to 110°C. and it is maintained at about 110° C. until about 70 to 80% of thetheoretical quantity of methanol is evolved, i.e. about 2 hours. Thereaction mixture is further stripped of volatiles by gradually reducingthe pressure inside the flask to about 120 mm Hg by aspirator.

To the resultant product is added 0.5 grams of methyl iodide in 100milliliters of O-dichlorobenzene. The resultant mixture is heated (inair) to reflux at 180° C. and maintained at this temperature for 8hours. The reaction mixture is cooled to about 100° C. to 110° C. It isessentially neutral, however, ethylene oxide is introduced to removemost of the residual acidity. The volatiles are removed from thereaction mixture by distillation at 110° C. and 8-15 mm Hg. The productis a viscous clear colorless liquid and is obtained in about 80-90%yield.

Analysis of the product confirmed the product to by poly(diethyleneglycol methylphosphonate) having an average n value of 14.

Analysis: % P = 18.0 (Theory 19.6). Acid No. = 0.3 mg KOH/g sample inwater. Acid No. = nil in CH₃ OH. OH No. = 60. Infrared analysis revealedOH, P=O and P-CH₃ bonds at 3450 cm⁻ ¹ 1230 cm⁻ ¹, and 1310 cm⁻ ¹,respectively.

EXAMPLE 3

A flask fitted with a mechanical stirrer, thermometer, and distillationhead is charged with 212 grams (2.0 moles) of diethylene glycol, 332grams (2.0 moles) of triethylphosphite, and 0.16 grams Na in 5milliliters of methanol. The reaction mixture is vigorously agitated andheated to from about 120° C. to 135° C. over a period of about 3 hours.The reaction is further stripped of volatiles under aspirator vacuum ata temperature of about 90° C. to 100° C.

The remaining product is dissolved in 150 grams of O-dichlorobenzene towhich 1.3 grams of methyl iodide is added. The mixture is heated (inair) to reflux and maintained at a temperature of about 170°-180° C. forabout 5 hours. The solvents are removed under aspirator pressure at atemperature of about 80°-110° C. for about 11/2 hours, with removal ofvolatiles. The product obtained is a viscous clear colorless liquidhaving an acid number in water of 8.12 mg of KOH per gram of sample.Analysis of the product confirmed the product to be poly(diethyleneglycol ethylphosphonate):

Analysis: % P = 17.1. OH No. = 94.

EXAMPLE 4

To a liter flask equipped with a mechanical stirrer, thermometer anddistillation head is charged 402 grams (3.0 mole) of dipropylene glycol,409.2 grams (3.3 mole) of trimethyl phosphite and 0.8 grams of sodiummethoxide (25% methanol). The reaction mixture is stirred and heated toabout 110° C. while 166 grams of volatiles are collected. The reactionmixture is then further stripped of volatiles under aspirator pressure.

To the remaining product is added 400 grams of O-dichlorobenzene. Thisreaction mixture is cooled to room temperature and 1.0 grams of methyliodide is added. The mixture is heated to 105° C. for 21/2 hours. Thetemperature is raised to 180° C. and the reaction is continued foranother 4 hours. The remaining volatiles are stripped under aspiratorpressure. The resultant product has an acid number in water of 1.68 mgof KOH per gram of sample. Analysis of the product confirms the productto be poly(dipropylene glycol methylphopshonate).

Analysis: OH No. = 46. % P = 14.9.

EXAMPLE 5

This example illustrates the preparation of the intermediatepoly(diethylene glycol methylphosphite).

To a 5 liter flask fitted with a mechanical stirrer, thermometer, anddistillation head is added 1,802.0 grams (17.0 moles) of diethyleneglycol and 2,318.8 grams (18.7 moles) of trimethyl phosphite. Thereaction mixture is stirred and heated to a temperature of 110° C. inthe absence of a transesterification catalyst while collecting volatilesfor about 41/2 hours. The reaction mixture is further stripped underaspirator pressure for about 1/2 hour. The product is collected in 95%yield.

EXAMPLE 6

The product made according to the procedure of Example 1 is incorporatedinto a polyurethane foam formulation as set forth in Table I, below.

                  TABLE I                                                         ______________________________________                                        Polyvol (Voranol CP 3000, made by Dow Chemical Co.                            a 3000 molecular weight propoxylated glycerol)                                                            700 gms.                                          Poly(diethylene glycol methylphosphonate)                                     prepared according to Example 1                                                                           49 gms.                                           Water                       28 gms.                                           Silicone surfactant L-548 made by Union Carbide                                                           7 gms.                                            N-ethyl morpholine          0.66 gms.                                         67% dimethylaminoethyl ether in dipropylene glycol                                                        0.46 gms.                                         33% 1,4-diazobicyclo [2.2.2] octane in dipropylene                            glycol                      0.98 gms.                                         Stannous octoate, 50% in dioctyl phthalate                                                                2.8 gms.                                          Toluene diisocyanate (80/20 isomers)                                                                      370 gms.                                          FOAM PROPERTIES                                                               Color                 White                                                   Odor                  None                                                    Density-                                                                      (lb./ft..sup.3)       1.47                                                    Air flow-                                                                     (ft..sup.3 /min.)     2.1                                                     Indent Load                                                                   Deflection-                                                                   (ILD, 25% lb.)         25                                                     FOAM FLAMMABILITY                                                             Motor Vehicle Safety Standard                                                                       SE/NBR                                                  (MVSS 302) Initial    (self-extin-                                                                  guishing, no                                                                  burning rate)                                           ______________________________________                                    

EXAMPLE 7

The product made according to the procedure of Example 4 is incorporatedinto a polyurethane foam formulation as set forth in Table II, below.

                  TABLE II                                                        ______________________________________                                        Polyol (Voranol CP 3000)    750 gms.                                          Poly(dipropylene glycol methylphosphonate)                                    according to Example 4      75 gms.                                           Water                       30 gms.                                           Silicone surfactant L-548   7.5 gms.                                          N-ethyl morpholine          1.2 gms.                                          67% dimethylaminoethyl ether in dipropylene glycol                                                        0.8 gms.                                          33% 1,4-diazobicyclo [2.2.2] octane in dipropylene                            glycol                      1.8 gms.                                          Stannous octoate, 50% in dioctyl phthalate                                                                3.0 gms.                                          Toluene diisocyanate (80/20 isomers)                                                                      418 gms.                                          FOAM PROPERTIES                                                                       Color (initial)                                                                           Yellow                                                            Odor        Some                                                              Density-                                                                      (lb./ft..sup.3)                                                                           1.41                                                              ILD, 25% lb.                                                                              29                                                                65% lb.     60                                                        FOAM FLAMMABILITY                                                                     MVSS 302                                                                      Initial     SE                                                                Dry heat 72 hrs/                                                              93°C.                                                                              SE                                                        ______________________________________                                    

What is claimed is:
 1. A flame retardant polyurethane foam containing asa chemically bonded integral part thereof, the residue of a polyalkyleneglycol alkyl or haloalkyl polyphosphonate characterized by an acidnumber in water of below about 15 mg. of KOH per gram of sample, havingthe formula: ##EQU6## wherein R is the residue of a polyalkylene glycolhaving the formula:

    HO --R"O ).sub.x H

wherein R" is an alkylene radical of 2 to about 20 carbon atoms and x isa number from 2 to about 20, R' is alkyl or haloalkyl and n is a numberin the range from about 2 to about
 50. 2. The polyurethane foam of claim1 wherein R is a residue of a polyalkylene glycol selected from thegroup consisting of diethylene glycol, dipropylene glycol, triethyleneglycol, tripropylene glycol and tributylene glycol.
 3. The polyurethanefoam of claim 1 wherein R' is C₁ -C₁₀ alkyl or C₁ -C₁₀ haloalkyl.
 4. Thepolyurethane foam of claim 1 wherein R is a residue of a polyalkyleneglycol selected from the group consisting of diethylene glycol,dipropylene glycol and tripropylene glycol, R' is a C₁ -C₁₀ alkyl or C₁-C₁₀ haloalkyl and n is a number from about 3 to about
 10. 5. Thepolyurethane foam of claim 1 wherein R is a residue of diethyleneglycol, R' is methyl and n is a number from about 3 to about
 10. 6. Aflame retardant polyurethane foam containing as a chemically bondedintegral part thereof, the residue of a polyalkylene glycol alkyl orhaloalkyl polyphosphonate resulting from a process of heating apolyalkylene glycol alkyl or haloalkyl polyphosphite of the formula:##EQU7## wherein R is the residue of a polyalkylene glycol having theformula:

    HO --R"O ).sub.x H

wherein R" is an alkylene radical of 2 to about 20 carbon atoms and x isa number from 2 to about 20, R' is alkyl or haloalkyl and n is a numberin the range from 2 to about 50, in the presence of a catalyticallyeffective amount of an Arbusov rearrangement catalyst at a temperaturein the range of from about 160° C. to about 230° C.
 7. The flameretardant polyurethane foam of claim 6 wherein said polyalkylene glycolalkyl or haloalkyl polyphosphite is selected from the group consistingof diethylene glycol alkyl or haloalkyl polyphosphite, dipropyleneglycol alkyl or haloalkyl polyphosphite, triethylene glycol alkyl orhaloalkyl polyphosphite, tripropylene glycol alkyl or haloalkylpolyphosphite, and tributylene glycol alkyl or haloalkyl polyphosphite.8. The flame retardant polyurethane foam of claim 6 wherein saidpolyalkylene glycol alkyl polyphosphite is diethylene glycol methylpolyphosphite and said Arbusov rearrangement catalyst is methyl iodide.9. The flame retardant polyurethane foam of claim 8 wherein saiddiethylene glycol methyl polyphosphite is prepared by transesterifyingtrimethyl phosphite with diethylene glycol in a mole ratio of about 1.1to 1, respectively.